JP2012019198A - Ignition coil for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition coil for an internal combustion engine which prevents water from easily intruding into a water retention chamber and easily discharges water accumulated in the water retention chamber.SOLUTION: An ignition coil for an internal combustion engine 1 includes a cylinder part 2 and a head part 4. A column part 44, forming a part of a ventilation passage which connects the interior of plug holes with the exterior of the plug holes through pieces of seal rubber 6, and a cover part 5 covering the column part 44 are provided on a side surface of the head part 4. The cover part 5 has a peripheral wall 55 covering the column part 44 in the upside and peripheral direction, a lower wall 51 covering a lower side of the peripheral wall 55, a water retention chamber 50 which is a space enclosed by the peripheral wall 55 and the lower wall 51, and communication holes 52 provided at the lower wall 51. A lower end surface of the lower wall 51 is located above a lower end surface of the peripheral wall 55.

Description

  The present invention relates to an ignition coil used for generating a spark between a pair of electrodes in a spark plug in an internal combustion engine.

  In an internal combustion engine, a cylinder portion of an ignition coil is inserted and placed in a plug hole provided in the engine, and ignition is performed by a spark plug attached to an end portion in the axial direction of the cylinder portion, thereby burning the engine. Further, ozone gas or the like accompanying high voltage is generated in the plug hole. Therefore, in order to ventilate these gases with the outside air outside the plug hole, a ventilation passage is formed in the ignition coil.

  Further, the pressure in the plug hole becomes a negative pressure by cooling the gas in the plug hole in the process of cooling the engine from the warmed state. At this time, if the ignition coil is flooded, water may enter the plug hole from the ventilation passage. For this reason, in order to prevent the ingress of water, a measure is taken to form a ventilation passage in a seal rubber or the like disposed between the ignition coil and the opening of the plug hole.

As an ignition coil (ignition device) devised in the ventilation passage, for example, there is one disclosed in Patent Document 1. In this ignition coil, a water retaining chamber capable of retaining water entering from the outside of the head at a side portion of the head disposed outside the plug hole, and a ventilation passage for communicating the water retaining chamber in the plug hole And form. Further, by retaining water in the water retention chamber, it is possible to reliably prevent water such as cleaning water from entering the plug hole and to easily drain water accumulated in the water retention chamber.
In the internal combustion engine ignition coil device disclosed in Patent Document 2, a space is formed in the upper portion of the connector case, a through hole is formed downward from the space, and the through hole is formed into a plug hole by a groove. It is disclosed to communicate.

Japanese Patent Laid-Open No. 2008-60188 JP 2007-303401 A

However, in Patent Document 1, when water flows down along the side wall of the head, there is a possibility that the water may enter and enter the ventilation port provided below the water retention chamber.
In the cited document 2, the space is formed by the cover that covers the connector case, and the space is ventilated by the gap formed between the cover and the connector case. Therefore, there is a possibility that the formation of the gap may vary, and if the gap is enlarged, water may enter, while if the gap is narrowed, sufficient ventilation may not be possible.

  The present invention has been made in view of such a conventional problem, and it is possible to make it difficult for water to enter the water retention chamber and to easily drain the water accumulated in the water retention chamber. An attempt is made to provide an ignition coil.

The present invention includes a cylindrical portion inserted into a plug hole of an internal combustion engine, a head connected to the cylindrical portion and disposed outside the plug hole, a radially outer side of the cylindrical portion, and the head. An ignition coil for an internal combustion engine provided with a seal rubber for preventing water from entering the plug hole from the opening of the plug hole.
On the side surface of the head portion, a column portion that forms a part of a ventilation passage that communicates the inside and the outside of the plug hole via the seal rubber, and the upper opening of the column portion is not blocked. And a cover part that covers the pillar part,
The cover part is
A peripheral wall covering the upper and circumferential directions of the pillar,
A lower wall portion for closing the lower portion of the peripheral wall portion;
A space formed by being surrounded by the peripheral wall portion and the lower wall portion, and a water retention chamber for temporarily storing water that has entered from the outside of the head; and
Provided in the lower wall portion, drains the water stored in the water retention chamber, and has a communication hole that communicates the water retention chamber and the outside of the plug hole,
The lower end face of the lower wall portion is located above the lower end face of the peripheral wall portion. The ignition coil for an internal combustion engine according to claim 1 is characterized.

  In the ignition coil for an internal combustion engine of the present invention, the atmosphere and the plug hole are communicated with each other through a communication hole, a water retention chamber, and a ventilation passage. Then, the gas in the plug hole can flow from the ventilation passage to the water retention chamber and can be exhausted from the communication hole of the water retention chamber to the outside of the ignition coil. Thereby, ventilation with the inside of a plug hole and the exterior can be performed.

  Further, in the process of performing combustion in the internal combustion engine using the ignition coil and cooling the internal combustion engine from the warmed state, the pressure in the plug hole becomes negative. At this time, if the head of the ignition coil is in a flooded state, water outside the head enters the water retention chamber through the communication hole, but this water must be temporarily stored in the water retention chamber. Can do. And since the upper opening part of a pillar part is opening to the water retention chamber, it can prevent that water permeates into the ventilation passage formed in the pillar part from the water retention chamber.

In addition, the lower end surface of the lower wall portion of the cover portion is located above the lower end surface of the peripheral wall portion. As a result, when the head is flooded and the water flows down through the cover portion, the water is prevented from flowing into the communication hole by the protruding portion which is a portion of the peripheral wall portion protruding downward from the lower wall portion. Can do. Therefore, it is possible to make it difficult for water to enter the water retention chamber, and it is possible to effectively prevent the ventilation of the gas in the plug hole from being affected by the intrusion of water. In addition, the formation of the protruding portion makes it difficult for a water film to stick to the communication hole, and can effectively drain the water accumulated in the water retention chamber.
In addition, when the head is submerged and water enters the water retention chamber, this water is communicated when the inside of the plug hole changes to positive pressure or normal pressure in the process of warming from the cooled state. It can be easily drained from the hole.
Thus, in the ignition coil of the present invention, a small amount of water is rebounded by the cover portion, and a large amount of water is stored by the water retention chamber and can be easily drained from the communication hole.

  Therefore, according to the ignition coil for an internal combustion engine of the present invention, it is possible to make it difficult for water to enter the water retention chamber and to easily drain the water accumulated in the water retention chamber.

1 is a perspective view showing an upper part of an ignition coil for an internal combustion engine in Embodiment 1. FIG. The top view which shows the upper part of the ignition coil for internal combustion engines in Example 1 in the state seen from upper direction. FIG. 3 is a diagram illustrating an upper part of an ignition coil for an internal combustion engine in the first embodiment, and is a cross-sectional explanatory view taken along line AA in FIG. 2. The perspective view shown in the state which looked at the cover part from the downward direction in Example 1. FIG. Sectional explanatory drawing which shows the periphery of the communication hole of a cover part in Example 1 in the state seen from the same direction as FIG. FIG. 3 is a diagram illustrating the periphery of the cover portion in the first embodiment, and is a cross-sectional explanatory view taken along line B-B in FIG. 2. The perspective view shown in the state which looked at the periphery of the width reduction slit in Example 1 from the downward direction. The top view which shows the communication state from a ventilation port in Example 1 to a plug hole. Cross-sectional explanatory drawing which shows the width reduction slit in Example 1 when the draining wall part is not formed. Sectional explanatory drawing which shows the width reduction slit at the time of forming the draining wall part in Example 1. FIG. The perspective view which shows the case where the width reduction slit in Example 1 is formed in the protrusion part side in a cover part. The perspective view shown in the state which looked at the periphery of the other width reduction slit in Example 1 from the downward direction. The perspective view shown in the state which looked at the periphery of the other width reduction slit in Example 1 from the downward direction. The perspective view shown in the state which looked at the periphery of the other width reduction slit in Example 1 from the downward direction. The perspective view which shows the upper part of the ignition coil for internal combustion engines in Example 2. FIG. FIG. 6 is a diagram illustrating an upper part of an ignition coil for an internal combustion engine in Embodiment 2, and is a cross-sectional explanatory view corresponding to the arrow AA in FIG. 2. FIG. 6 is a diagram illustrating the periphery of a cover portion in Embodiment 2, and is a cross-sectional explanatory diagram corresponding to the view taken along line B-B in FIG. 2. Sectional explanatory drawing shown in the state which looked at the periphery of the cover part from the downward direction in Example 2. FIG. FIG. 10 is a diagram illustrating a modification of the lower wall portion in the second embodiment, and is a cross-sectional explanatory diagram corresponding to the line AA in FIG. 2. FIG. 10 is a diagram illustrating a modification of the column portion in the second embodiment, and is a cross-sectional explanatory diagram corresponding to the line AA in FIG. 2.

A preferred embodiment of the above-described ignition coil for an internal combustion engine of the present invention will be described.
In the ignition coil for an internal combustion engine according to the present invention, the primary coil and the secondary coil arranged concentrically can be arranged on either the cylinder part or the head part. A high voltage terminal connected to the high voltage winding end of the secondary coil and electrically connecting the high voltage winding end to the spark plug can be disposed on the cylindrical portion.
Further, the lower part of the cover part means a vertical direction, and the upper part of the cover part means a direction opposite to the vertical direction. The outside of the head means the outside where the head is exposed to the outside air.

Further, the communication hole is preferably formed as a width reducing slit whose opening width is reduced from one to the other (claim 2).
In this case, the distribution of the surface tension of water generated in the width reducing slit can be made non-uniform. That is, the surface tension acting on the portion with the small width can be increased as compared with the portion with the large width reduction slit. Thereby, the water which gathers in a width reduction slit can be drawn near to a part with a small width. Therefore, it is possible to make it difficult for a water film to be generated in the communication hole, and to easily drain the water in the water retention chamber.

Further, a drain wall portion for cutting off water accumulated in the portion where the opening width is reduced can be provided at the edge of the width reduction slit so as to face downward.
In this case, the water collected in the communication hole can be made to easily flow down in the vertical direction by the surface tension of the water generated in the draining wall. Further, the water draining wall portion can make it difficult for water to enter the width reduction slit from obliquely below.

In addition, a baffle plate is provided in the water retention chamber so as to block water between the communication hole and the upper opening so that water entering from the outside does not directly enter the upper opening through the communication hole, and It is preferable that a communication gap is formed between the outer peripheral side surface of the baffle plate and the inner peripheral surface of the peripheral wall portion at a position deviated from directly above the communication hole in the axial direction.
In this case, the position where the communication hole is formed and the position where the communication gap is formed are shifted laterally, and the maze structure from the communication hole to the upper opening of the column portion can be formed by the baffle plate. Thereby, it is possible to more effectively prevent water from entering the plug hole.

The communication hole is formed as a gap between the inner peripheral side surface of the lower wall portion and the outer peripheral surface of the column portion, and the width of the gap is preferably non-uniform.
In this case, the surface tension due to water adhering to the communication hole as the gap can be made different at each part of the gap to effectively prevent the formation of a water film over the entire communication hole. In this case, the drainage effect of the water accumulated in the water retention chamber can be enhanced.

The gap can be formed from a wide gap portion having a wide width and a narrow gap portion having a narrower width than the wide gap portion.
In this case, it is possible to effectively prevent the formation of a water film over the entire gap by making the surface tension due to water adhering to the wide gap portion and the narrow gap portion different.

The upper surface of the lower wall portion is preferably inclined downward in the direction in which the communication hole is formed (Claim 6).
In this case, the water that has entered the water retention chamber can be drained effectively.

Embodiments of the ignition coil for an internal combustion engine according to the present invention will be described below with reference to the drawings.
Example 1
As shown in FIGS. 1 and 3, the ignition coil 1 for the internal combustion engine of the present example is connected to the cylindrical portion 2 inserted into the plug hole 81 of the internal combustion engine and the cylindrical portion 2, and outside the plug hole 81. The head 4 to be disposed, and a seal disposed outside the cylinder portion 2 in the radial direction and below the head 4 to prevent water from entering the plug hole 81 from the opening of the plug hole 81 And a rubber 6.
On the side surface of the head 4, a column part 44 that forms a part of a ventilation passage that connects the inside and the outside of the plug hole 81 via the seal rubber 6, and an upper opening 442 in the ventilation port 441 of the column part 44. The cover part which covers the pillar part 44 without obstruct | occluding is provided.

The cover portion 5 is a space formed by being surrounded by a peripheral wall portion 55 that covers the upper portion and the circumferential direction of the column portion 44, a lower wall portion 51 that covers the lower portion of the peripheral wall portion 55, and the peripheral wall portion 55 and the lower wall portion 51. And a communication hole 52 provided in the lower wall portion 51. The water retention chamber 50 is formed to temporarily store water that has entered from the outside of the head 4, and the communication hole 52 drains the water stored in the water retention chamber 50, and the water retention chamber 50 and the plug hole. 81 is formed to communicate with the outside.
The lower end surface of the lower wall portion 51 is located above the lower end surface of the peripheral wall portion 55, and a protruding portion 53 that protrudes from the lower end surface of the lower wall portion 51 is formed at the lower end portion of the peripheral wall portion 55. Yes. The protruding portion 53 is formed on the entire periphery excluding the side wall portion 411 of the head portion 4 at the lower end of the cover portion 5.

Hereinafter, the ignition coil 1 for an internal combustion engine according to the present embodiment will be described in detail with reference to FIGS.
As shown in FIGS. 1 and 3, the ignition coil 1 of this example is of a stick type, and accommodates a primary coil 21 and a secondary coil 22 arranged concentrically to form a cylindrical portion 2. The head 4 is connected to the upper side of the part 2 in the axial direction. The ignition coil 1 can be a rectangular type, and the primary coil 21 and the secondary coil 22 can be accommodated in the head 4.
Further, the ignition coil 1 is used by attaching the cylindrical portion 2 to a spark plug attached in the plug hole 81 of the cylinder head of the engine 8 (not shown).

  As shown in FIG. 3, the cylindrical portion 2 is formed by arranging a primary coil 21 and a secondary coil 22 concentrically arranged on the inner and outer circumferences in the head 3. The primary coil 21 is formed by winding an insulating-coated primary winding around the outer periphery of a primary spool 211 made of a thermoplastic resin having an annular cross section. The secondary coil 22 is formed by winding an insulating-coated secondary winding around the outer periphery of a secondary spool 221 made of a thermoplastic resin having an annular cross section. Further, the secondary winding has a smaller diameter than the primary winding, and the secondary winding is wound around the secondary spool 221 more times than the primary winding.

A rod-shaped central core 23 made of a magnetic material is arranged on the inner peripheral side of the primary coil 21 and the secondary coil 22, and a cylindrical shape made of a magnetic material is arranged on the outer peripheral side of the primary coil 21 and the secondary coil 22. The outer peripheral core 24 is arranged. In this example, the secondary coil 22 is inserted on the inner peripheral side of the primary coil 21, and the central core 23 is inserted on the inner peripheral side of the secondary coil 22.
Further, the central core 23, the secondary coil 22, the primary coil 21 and the outer core 24 are accommodated in the head 3. The head 4 in this example is extended from the head 3 by integral molding of resin.

As shown in FIG. 3, an igniter 47 including a switching circuit for energizing and interrupting the primary coil 21 is arranged in the head 4.
The head 4 of this example includes a connector connecting portion 42 for electrically connecting the ignition coil 1 to an ECU (electronic control unit) and the like, and an ignition coil 1 to the case main body 41 that houses the igniter 47 and the like. 8 is provided with a flange portion 43 for attachment to 8.
A seal rubber 6 for preventing water from entering the plug hole 81 is attached to the opening 811 of the plug hole 81 of the engine 8 below the head 4 (case main body 41). .

  As shown in FIGS. 1 to 3 and 6, the column portion 44 of this example is formed as a portion that protrudes in the radial direction of the ignition coil 1 outside the side wall portion 411 of the case main body portion 41. The column part 44 is formed as a substantially semicircular cylindrical part. A ventilation passage forming portion 45 is provided at a lower portion of the case body portion 41 and below the column portion 44 by partially inflating the case body portion 41 to the side. The ventilation port 441 of the column 44 communicates with a ventilation passage 451 formed between the ventilation passage forming portion 45 and the seal rubber 6.

A ventilation passage 31 for communicating the ventilation passage 451 and the plug hole 81 is continuously formed in the outer peripheral portion of the head 3 and the axial end portion of the head 4. As shown in FIG. 6, the formation position of the ventilation passage 31 can be a position shifted in the circumferential direction with respect to the position where the ventilation port 441 communicates with the ventilation passage 451. Further, FIG. 8 shows a ventilation passage 451 connecting the ventilation port 441 and the ventilation passage 31 in plan view. The ventilation port 441 communicates with the plug hole 81 via the ventilation passage 451 and the ventilation passage 31.
In FIG. 3, the positions in the circumferential direction that form the ventilation ports 441 and the ventilation passages 451 are matched to simplify the illustration. The ventilation passage 31 includes a groove formed continuously in the axial direction of the head 3 and the radial direction of the head 4. The ventilation passage 31 can also be formed with respect to the seal rubber 6.

  As shown in FIGS. 1 and 2, the cover portion 5 of this example is provided by performing ultrasonic welding on the side wall portion 411 of the case main body portion 41 of the head 4 after resin molding. . The cover 5 is provided on the outer periphery of the case main body 41 at a position different from the position where the connector connecting portion 42 and the flange portion 43 are provided. The cover part 5 is formed so as to cover the upper part of the pillar part 44 so as to cover the upper end of the ventilation port 441 in the pillar part 44. The cover part 5 can also be provided on the side wall part 411 of the case main body part 41 by bonding or the like.

Moreover, as shown in FIG. 4, the cover part 5 is formed in a curved shape on the upper side and the side, and is provided with a flat lower wall part 51 on the lower side. The cover portion 5 is formed by forming a flange portion 501 for welding on the upper and side edges. As shown in FIG. 1, the cover 5 is provided on the case body 41 by welding the flange portion 501 to the side wall 411 of the case body 41.
As shown in FIG. 6, the lower wall portion 51 of this example is disposed at an intermediate position in the vertical direction of the column portion 44. The protruding portion 53 of this example is provided as a portion protruding downward from the lower wall portion 51 by providing the lower wall portion 51 at a position slightly above the lower end of the side portion of the cover portion 5.

  As shown in FIG. 4 and FIG. 7, the communication hole 52 of this example is formed as a width reducing slit 52 that reduces the opening width from one side to the other in the lower wall portion 51 of the cover portion 5. The width reducing slit 52 is formed at the left and right positions with respect to the column portion 44. The width reducing slit 52 is positioned on the end side of the lower wall portion 51 on the side where the width is increased. The width reducing slit 52 is formed at the end of the lower wall 51 on the side wall 411 side of the head 4.

The effect of forming the width reducing slit 52 in the lower wall portion 51 can be described as follows.
Temporarily, when the rectangular through hole is formed in the lower wall portion 51, the water W collected in the through hole is balanced by the surface tension acting on the water W from the side wall surfaces of the four sides of the through hole. It will stay in the through hole. On the other hand, when the slit shape is formed by opening the side wall surface of one side of the rectangular through hole, the surface tension does not act on the water W from the opened portion, and the balance of the surface tension acting on the water W is lost. . Then, the water W is pulled by the surface tension to the side opposite to the opened side.
In particular, in this example, as shown in FIG. 7, the water W is drawn to the reduced side wall surface 525 located on the opposite side to the opened side by the width reducing slit 52 that reduces the width. Thereby, it is possible to make it difficult for a water film to be generated in the width reducing slit 52, and it is possible to easily drain the water (water accumulated in the lower wall portion 51) W in the water retention chamber 50.

As shown in FIG. 5, the width reducing slit 52 is formed by cutting out from the end surface on the inner peripheral side of the lower wall portion 51. As shown in FIGS. 3 and 6, a slight gap 52 </ b> A is formed between the lower wall portion 51 of the cover portion 5 and the column portion 44. In order to make it difficult for water W to enter the water retention chamber 50 from the gap 52A, a flange 522 that protrudes downward is formed around the pillar portion 44 in the lower wall portion 51 of the cover portion 5.
Note that the flange portion 522 is formed along with the formation of the gap 52A. When the gap 52A is not formed between the lower wall portion 51 and the column portion 44, the flange portion 522 can be omitted.

  Further, as shown in FIG. 7, a drain wall portion 521 for cutting water W collected on the reduced side wall surface 525, which is a portion where the opening width is reduced, is provided at the edge of the width reduction slit 52 so as to face downward. is there. The draining wall portion 521 is provided on one of the left and right side wall surfaces 526 in the width reducing slit 52. The draining wall portion 521 is provided as a taper wall whose protruding amount increases toward the side where the width decreases.

Moreover, the effect by providing the draining wall part 521 in the width reduction slit 52 can be demonstrated as follows.
FIG. 9 is a cross-sectional view of the periphery of the reduced side wall surface 525 of the width reducing slit 52 when the drain wall portion 521 is not formed. In this case, in this case, the sum of the surface tension T acting on the water W from the left and right side wall surfaces 526 and the gravity P acting on the water W are balanced in the vertical direction, and the reduced side wall surface 525 of the width reducing slit 52 is shown in FIG. It is considered that a small amount of water W remains in the vicinity of.

In FIG. 10, the periphery of the reduced side wall surface 525 of the width reducing slit 52 when the drain wall portion 521 is formed is shown in cross section. In this figure, in this case, the surface tension T1 acting on the water W from the side wall surface 526A on the side where the drain wall portion 521 is formed is changed from the side wall surface 526B on the side where the drain wall portion 521 is not formed to the water W. It becomes larger than the acting surface tension T2. Thereby, in the vertical balance, the gravity P acting on the water W becomes larger than the sum of the surface tensions T1, T2 acting on the water W from the left and right side wall surfaces 526A, 526B. Therefore, the water W remaining on the reduced side wall surface 525 of the width reducing slit 52 can flow down in the vertical direction along the drain wall portion 521. Further, the water draining wall portion 521 can make it difficult for water W to enter the width reducing slit 52 from obliquely below.
In this example, the reason for providing the drain wall portion 521 only on one side wall surface 526A is to break the balance of the surface tensions T1 and T2 acting on the water W from the left and right side wall surfaces 526A and 526B. Therefore, the drain wall portion 521 can have various structures that can break the balance of the surface tension acting on the water W from which direction.

  The volume of the water retention chamber 50 in this example is formed to be larger than the volume shrinkage of the gas generated when the gas in the plug hole 81 is cooled and the plug hole 81 becomes negative pressure. Thereby, it is possible to prevent the water sucked from the communication hole 52 at the negative pressure of the plug hole 81 from reaching the upper end of the ventilation port 441 via the water retention chamber 50.

  Although not shown, a spark plug is attached to the bottom of the plug hole 81, and the ignition coil 1 of this example is attached to the spark plug at the lower end in the axial direction of the head 3. have. The plug mounting portion includes a rubber plug cap into which a lever portion of the spark plug is inserted, a high voltage terminal connected to the high voltage winding end portion of the secondary coil 22, and a coil connected to the high voltage terminal. And a spring. The lower end side in the axial direction of the coil spring is electrically connected to a terminal portion formed at the tip of the insulator portion of the spark plug.

  Further, as shown in FIG. 3, a filling resin 15 is filled in the gap of the ignition coil 1 surrounded by the head 3 and the head 4. The filling resin 15 in this example is an epoxy resin as a thermosetting resin. The filling resin 15 in the ignition coil 1 is assembled in a vacuum state in the gap of the ignition coil 1 after the components of the ignition coil 1 are assembled, and a liquid epoxy resin is placed in the vacuum gap. And then cured by curing the epoxy resin.

  In the ignition coil 1, when a current is passed through the primary coil 21 by a pulsed spark generation signal from the ECU, a magnetic field that passes through the central core 23 and the outer peripheral core 24 is formed. Next, when the current flowing through the primary coil 21 is interrupted, an induction magnetic field passing through the central core 23 and the outer peripheral core 24 is formed in a direction opposite to the magnetic field formation direction. And by this induction magnetic field formation, a high voltage induced electromotive force (back electromotive force) is generated in the secondary coil 22, and a spark can be generated between a pair of electrodes in the spark plug attached to the ignition coil 1. .

  In the internal combustion engine ignition coil 1 of this example, the atmosphere and the inside of the plug hole 81 are communicated with each other through the communication hole 52, the water retention chamber 50, the ventilation port 441, and the ventilation passages 31 and 451. The gas in the plug hole 81 can flow from the ventilation passage 31 to the ventilation passage 451, the ventilation port 441, and the water retention chamber 50, and can be exhausted from the communication hole 52 of the water retention chamber 50 to the outside of the ignition coil 1. Thereby, ventilation between the plug hole 81 and the outside can be performed.

  Further, in the process of performing combustion in the engine 8 using the ignition coil 1 and cooling the engine 8 from a warmed state, the inside of the plug hole 81 becomes negative pressure. At this time, if the head 4 of the ignition coil 1 is in a flooded state, water outside the head 4 enters the water retention chamber 50 through the communication hole 52, but this water enters the water retention chamber 50. Can be temporarily accommodated. The upper opening 442 of the ventilation port 441 is open to the water retention chamber 50, thereby preventing water from entering the ventilation port 441 from the water retention chamber 50.

Further, a projecting portion 53 projects downward from the entire periphery of the lower end of the cover portion 5 except the side wall portion 411 of the head portion 4. Thereby, when the head 4 is flooded and the water flows down through the cover portion 5, the protrusion 53 can prevent the water from flowing into the communication hole 52. Therefore, it is possible to make it difficult for water to enter the water retention chamber 50, and it is possible to effectively prevent the gas ventilation in the plug hole 81 from being affected by the intrusion of water. Further, the formation of the protruding portion 53 can make it difficult for the water film to stick to the communication hole 52, and can effectively drain the water accumulated in the water retention chamber 50.
Further, when the head 4 is submerged or the like and water enters the water retention chamber 50, this water is heated to a positive pressure or normal pressure in the plug hole 81 during the process of warming the engine 8 from the cooled state. When changing, it can be easily drained from the communication hole 52.

Further, as shown in FIG. 7, when a small amount of water W adheres to the width reduction slit 52, the water W can be moved to the side where the width is reduced by the surface tension generated thereby. And the water W which moved to the reduction | decrease side wall surface 525 which is a part which the width | variety reduced can be made to flow down through the draining wall part 521. FIG. Thereby, the water W adhering to the width reduction slit 52 can be quickly flowed down, and the presence of the water W can be prevented from affecting the ventilation. In addition, when a small amount of water W remains in the vicinity of the reduced side wall surface 525, the water W flows down from the side end portion 521A near the reduced side wall surface 525 in the drain wall portion 521. On the other hand, when the amount of water W is large, it is considered that the water W may flow down along almost the entire side surface 521B of the draining wall 521.
Thus, in the ignition coil 1 of this example, a small amount of water is rebounded by the cover 5, and a large amount of water is stored by the water retention chamber 50 and can be easily drained from the communication hole 52.

  Moreover, in the ignition coil 1 of this example, when the periphery of the column part 44 provided with the ventilation port 441 is flooded, water scattered from above or from the side does not enter the upper end of the ventilation port 441 by the cover unit 5. The water which scatters from below is prevented from entering the upper end of the ventilation port 441 by the lower wall portion 51. Further, depending on the amount, direction, and flow rate of water, water may enter the water retention chamber 50 from the communication hole (slit) 52. In this case, water can be stored in the water retention chamber 50 and drained easily from the water retention chamber 50 through the slit 52.

Therefore, according to the ignition coil 1 for an internal combustion engine of the present example, it is possible to prevent water from entering the plug hole 81 by accumulating water in the water retention chamber 50 and to prevent water from entering the water retention chamber 50. Can be prevented from entering, and the water accumulated in the water retention chamber 50 can be easily drained.
In this example, the ventilation type drainage structure provided with the column part 44 and the cover part 5 is a stick type ignition in which the cylindrical part 2 in which the primary coil 21 and the secondary coil 22 are inserted and arranged in the plug hole 81 is formed. Coil 1 is shown. On the other hand, the ventilation drainage structure can also be adopted in the rectangular type ignition coil 1 in which the primary coil 21 and the secondary coil 22 are accommodated in the head 4.

The width reducing slit 52 as the communication hole may have the following various structures.
As shown in FIG. 11, the width reducing slit 52 can be formed on the protruding portion 53 side of the cover portion 5. In this case, the width reducing slit 52 can be formed adjacent to the cover main body portion 55, and the draining wall portion 521 can be connected to the protruding portion 53.
As shown in FIG. 12, in the width reducing slit 52, tapered chamfered portions 527 can be formed at the upper end corners of the left and right side wall surfaces 526 and the upper end corners of the reduced side wall surfaces 525. In this case, the formation of the chamfered portion 527 makes it easy to collect the water W on the lower wall portion 51 in the width reducing slit 52.

Further, as shown in FIG. 13, the draining wall portion 521 can be formed obliquely with respect to the lower wall portion 51 instead of being perpendicular to the lower wall portion 51. The drain wall portion 521 can be inclined so as to form an acute corner portion between the drain wall portion 521 and the lower wall portion 51. In this case, the water W can be more easily attracted to the side of the draining wall portion 521 by the surface tension.
Further, as shown in FIG. 14, the drain wall portion 521 is formed only on a portion of the one side wall surface 526 close to the reduced side wall surface 525 in addition to being formed on the entire one side wall surface 526 in the width reducing slit 52. be able to.

(Example 2)
This example is an example of the cover 5 and the ignition coil 1 that is different from the first embodiment in the configuration in the cover 5.
As shown in FIGS. 15 to 17, the communication hole 52 </ b> B and the upper opening 442 are prevented from entering the water retaining chamber 50 from the outside through the communication hole 52 </ b> B and directly into the upper opening 442 of the ventilation port 441. A baffle plate 54 is provided to block between the two. The baffle plate 54 is provided in the cover portion 5 so as to cover the upper side of the communication hole 52B at an upper position with respect to the lower wall portion 51 thereof.

The baffle plate 54 can form a maze structure from the communication hole 52 </ b> B to the upper end of the ventilation port 441, and can more effectively prevent water from entering the plug hole 81. The upper surface 511 of the lower wall portion 51 of the cover portion 5 is inclined downward in the direction in which the communication hole 52B is formed.
The communication hole 52 </ b> B of this example is formed as a gap 52 </ b> B around the column part 44 in the lower wall part 51 of the cover part 5.
The lower wall portion 51 is formed by inclining only the upper surface 511 and the lower surface 512 is formed perpendicular to the cover main body portion 55. On the other hand, as shown in FIG. 19, the lower wall part 51 can also be formed by inclining the whole (the upper surface 511 and the lower surface 512).

  As shown in FIGS. 16 and 17, the baffle plate 54 is provided around the column portion 44 at a position above the lower wall portion 51. A communication gap 541 is formed between the outer peripheral side surface of the baffle plate 54 and the inner peripheral surface of the peripheral wall portion 55 of the cover portion 5 at a position deviating from the position directly above the communication hole 52B in the axial direction. More specifically, the baffle plate 54 and the column portion 44 are closed, and a communication gap 541 is provided between the outer periphery of the baffle plate 54 and the inner periphery of the cover portion 5. And the penetration | invasion of the water into the plug hole 81 can be prevented more effectively by shifting the formation location of the connection hole 52B, and the formation location of the communication gap 541 to a horizontal direction.

  As shown in FIG. 18, the communication hole 52 </ b> B of this example is a gap 52 </ b> B between the inner peripheral side surface of the lower wall portion 51 and the outer peripheral surface of the column portion 44, and the gap 52 </ b> B has a nonuniform width. Can be formed. More specifically, the gap 52 </ b> B as the communication hole 52 </ b> B can be formed by combining a wide gap portion 523 having a wide width and a narrow gap portion 524 having a narrower width than the wide gap portion 523. The wide gap portion 523 can be formed so that its width is 1 mm or more larger than the width of the narrow gap portion 524. The surface tension due to water adhering to the wide gap portion 523 and the narrow gap portion 524 can be made different to effectively prevent the formation of a water film over the entire gap 52B. In addition, the drainage effect of the water accumulated in the water retention chamber 50 can be enhanced.

In addition to forming the column portion 44 adjacent to the side wall portion 411 of the head 4 as shown in FIG. 16, as shown in FIG. 20, the center portion of the lower wall portion 51 or the cover of the cover portion 5 is formed. It can also be formed in a portion close to the main body portion 55. In this case, the communication gap 541 can be formed between the side wall portion 411 of the head 4 and the end portion of the baffle plate 54.
Also in the ignition coil 1 of this example, other configurations are the same as those of the first embodiment, and the same effects as those of the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 Internal combustion engine ignition coil 2 Cylindrical part 21 Primary coil 22 Secondary coil 3 Head part 31 Ventilation passage 4 Head part 41 Case main-body part 44 Column part 441 Ventilation port 442 Upper opening part 45 Ventilation passage formation part 451 Ventilation passage 5 Cover part 50 Water Retention Chamber 51 Lower Wall 52 Connection Hole 53 Projection 54 Baffle Plate 6 Seal Rubber 8 Engine 81 Plug Hole

Claims (6)

A cylindrical portion inserted into a plug hole of an internal combustion engine, a head connected to the cylindrical portion and disposed outside the plug hole, a radially outer side of the cylindrical portion, and below the head In the ignition coil for an internal combustion engine, which is disposed and includes a seal rubber for preventing water from entering the plug hole from the opening of the plug hole.
On the side surface of the head portion, a column portion that forms a part of a ventilation passage that communicates the inside and the outside of the plug hole via the seal rubber, and the upper opening of the column portion is not blocked. And a cover part that covers the pillar part,
The cover part is
A peripheral wall covering the upper and circumferential directions of the pillar,
A lower wall portion for closing the lower portion of the peripheral wall portion;
A space formed by being surrounded by the peripheral wall portion and the lower wall portion, and a water retention chamber for temporarily storing water that has entered from the outside of the head; and
Provided in the lower wall portion, drains the water stored in the water retention chamber, and has a communication hole that communicates the water retention chamber and the outside of the plug hole,
An ignition coil for an internal combustion engine, wherein a lower end surface of the lower wall portion is located above a lower end surface of the peripheral wall portion.   2. The ignition coil for an internal combustion engine according to claim 1, wherein the communication hole is formed as a width reducing slit whose opening width is reduced from one to the other.   The internal combustion engine ignition according to claim 2, wherein a draining wall portion for cutting water accumulated in a portion where the opening width is reduced is provided at an edge portion of the width reduction slit. coil.   A baffle plate is provided in the water retention chamber to block between the communication hole and the upper opening so that water entering from the outside does not directly enter the upper opening through the communication hole, and 4. A communication gap is formed between the outer peripheral side surface of the baffle plate and the inner peripheral surface of the peripheral wall portion at a position deviated from directly above the connecting hole in the axial direction. The ignition coil for internal combustion engines as described in any one of Claims.   5. The communication hole according to claim 1, wherein the communication hole is formed as a gap between an inner peripheral side surface of the lower wall portion and an outer peripheral surface of the column portion, and the width of the gap is not uniform. The ignition coil for internal combustion engines as described in any one of Claims.   The ignition coil for an internal combustion engine according to any one of claims 1 to 5, wherein an upper surface of the lower wall portion is inclined downward in a direction in which the communication hole is formed.

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